For RNA-seq, RNA was isolated using TRNzol reagent. After DNase I treatment, rRNA was removed using QIAseq FastSelect RNA Removal Kit (QIAGEN). For RIP-seq, chromatin RNA was extracted, then fragmented to about 100-300 nt-long, and incubated with anti-m6A antibody (Millipore). Then the mixture was subjected to Dynabeads protein G binding. After washing, the bound RNA was eluted by RLT and retrieved by RNeasy Plus Micro Kit (Qiagen). H3K9me2 ChIP-seq was performed using the iDeal ChIP-seq Kit for Histones (Diagenode). For KDM3B, METTL3 and Pol II ChIP-seq, cells were crosslinked, sonicated, and subjected to ChIP. RNA-seq libraries were generated using NEBNext Ultra Directional RNA Library Prep Kit for Illumina (NEB). RIP-seq libraries were generated using SMARTer Stranded Total RNA-Seq Kit v2 -Pico Input Mammalian (Takara) following the manual. ChIP-seq libraries were generated using NEBNext Ultra DNA Library Prep Kit for Illumina. RNA-seq, RIP-seq and ChIP-seq